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Possibly faster GL timestamp query result check #1404

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Possibly faster GL timestamp query result check #1404

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16cfd25
potentially faster timestamp query result check
slomp Jun 16, 2026
dd6962b
use queryId arg, not m_tail member
slomp Jun 16, 2026
704b5c4
refactor sentinel value
slomp Jun 16, 2026
32b712c
force inline helper method
slomp Jun 16, 2026
22abcd2
cosmetic: making things a bit more idiomatic
slomp Jun 16, 2026
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39 changes: 34 additions & 5 deletions public/tracy/TracyOpenGL.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -102,6 +102,7 @@ class GpuCtx
: m_context( GetGpuCtxCounter().fetch_add( 1, std::memory_order_relaxed ) )
, m_head( 0 )
, m_tail( 0 )
, m_supportsQueryBufferObject( false )
{
ZoneScopedC( Color::Red4 );

Expand All @@ -113,6 +114,14 @@ class GpuCtx
"OpenGL context does not support GL_ARB_timer_query." );
}

// check for GL_QUERY_RESULT_NO_WAIT support
m_supportsQueryBufferObject = CheckFeature( "GL_ARB_query_buffer_object" );
if( !m_supportsQueryBufferObject )
{
Profiler::LogString( MessageSourceType::Tracy, MessageSeverity::Info, 0, 0,
"OpenGL context does not support GL_ARB_query_buffer_object." );
}

GLint bits;
glGetQueryiv( GL_TIMESTAMP, GL_QUERY_COUNTER_BITS, &bits );
if( bits == 0 )
Expand Down Expand Up @@ -197,12 +206,8 @@ class GpuCtx

while( m_tail != m_head )
{
GLint available;
glGetQueryObjectiv( m_query[m_tail], GL_QUERY_RESULT_AVAILABLE, &available );
if( !available ) return;

uint64_t time;
glGetQueryObjectui64v( m_query[m_tail], GL_QUERY_RESULT, &time );
if( !GetTimestamp(time, m_tail) ) return;

TracyLfqPrepare( QueueType::GpuTime );
MemWrite( &item->gpuTime.gpuTime, (int64_t)time );
Expand Down Expand Up @@ -239,6 +244,28 @@ class GpuCtx
return exts && strstr( exts, feature ) != nullptr;
}

tracy_force_inline bool GetTimestamp( uint64_t& timestamp, unsigned int queryId )
{
if( m_supportsQueryBufferObject )
{
constexpr uint64_t sentinel = ~uint64_t(0);
uint64_t time = sentinel;
glGetQueryObjectui64v( m_query[queryId], GL_QUERY_RESULT_NO_WAIT, &time );
if ( time == sentinel ) return false;
timestamp = time;
}
else
{
GLint available;
glGetQueryObjectiv( m_query[queryId], GL_QUERY_RESULT_AVAILABLE, &available );
if( available == GL_FALSE ) return false;
uint64_t time;
glGetQueryObjectui64v( m_query[queryId], GL_QUERY_RESULT, &time );
timestamp = time;
}
return true;
}

#ifdef TRACY_OPENGL_AUTO_CALIBRATION
// Monotonic host ns for the inter-calibration interval (cpuDelta), kept
// separate from Profiler::GetTime() as in the D3D12/Vulkan backends.
Expand Down Expand Up @@ -298,6 +325,8 @@ class GpuCtx
#ifdef TRACY_OPENGL_AUTO_CALIBRATION
int64_t m_prevCalibration; // host-ns timestamp of the last emitted calibration
#endif

bool m_supportsQueryBufferObject;
};

class GpuCtxScope
Expand Down
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